The invention relates generally to power-driven conveyors and, more particularly, to conveyors having conveyor belts with article-supporting rollers that rotate on axes oblique to the direction of belt travel when engaged by bearing surfaces sequentially activated into contact with the rollers in contiguous zones along the conveyor.
Modular plastic conveyor belts with article-supporting rollers extending past outer and inner belt surfaces are used in many conveying applications. When the rollers are arranged to rotate on axes oblique to the direction of belt travel and are contacted by bearing surfaces at the inner belt surface, the rollers can propel conveyed articles toward a side of the belt as it advances. The bearing surfaces in a region of the conveyor may be raised into an activated position in contact with the rollers from a lowered, deactivated position out of contact with the rollers. The bearing surfaces are conventionally flat wear surfaces or cylindrical outer surfaces of rollers that are free to rotate on axes in the direction of belt travel. Sometimes it is required that consecutive conveyed articles be directed to different locations. For example, a leading article may have to be diverted off the side of the belt to another conveyor while a trailing article may have to continue undiverted along the conveyor. If the bearing surfaces activate the rollers when the leading article is riding atop them, the article will be directed off the side of the belt, after which the bearing surfaces are lowered to deactivate the rollers to allow the trailing article to ride with the belt without being diverted. The length of the bearing surface section raised and lowered defines the minimum spacing between consecutive articles because no two articles should be on the belt in an activated region at the same time.
This conveying scheme is effective in many applications, such as article sorting. But moving an article across the width of a wide belt requires an extended-length activated region and, consequently, a greater spacing between consecutive conveyed articles. The increased spacing reduces conveyor throughput.
Thus, there is a need for a conveyor that can rapidly divert closely spaced articles for sorting and other conveying applications.